Offer from ex close after tango (6)
I believe the answer is:
extend
'offer' is the definition.
(I know that offer can be written as extend)
'ex close after tango' is the wordplay.
'close' becomes 'end' (I've seen this in another clue).
'after' means one lot of letters go next to another.
'tango' becomes 'T' (phonetic alphabet: alpha, bravo, charlie etc.).
'end' after 't' is 'tend'.
'ex'+'tend'='EXTEND'
'from' acts as a link.
(Other definitions for extend that I've seen before include "Enlarge, widen" , "continue" , "Provide challenge" , "Reach out, say the hand of friendship" , "Hold out or stretch out" .)